Thread severing device for sewing machines



` T. A. ANDERSON THREAD ASEVERING DEVICE-FOR SEWINGMACHINES Aug. 1s,1942.

Fiied May 9, 1939 4tice to pass the oFFlcE-.j

" s Gnmcsroas Them. A. Anderton, mann, c...

assignments, to The Singel-Manufacturing Company, Elixabe mesne of NewJersey N. J.. a corporation Application my s, im, sei-ni No. l212,661

This invention relates to thread severing means and more particularly tothread severing means associated with and forming a part of a sewingmachine.

LIn the manufacture of bags, and in many other` instances where articlesare stitched one after another it is the pracarticles through a sewingmaat a high rate of speed practithey can be fed to the sewing operator.'without stopping or speed of operation of the sewchine operating callyas fast as machine by the slowing down the ling machine during theinterval between the final stitching operation on one article and theinitial stitching operation on the succeeding article, with the resultthat the successive articles are connected by a thread chain or a seriesof thread loops which have of the threads connecting such articlesordinarily is done by the operator with a pairof scissors, even thoughsuch a method of severing the threads between the articles-is notsatisfactory as it necessitates a separate operation requiring anappreciable amount of the operators time, and, as only one cut betweenarticles is made, it leaves a tail of thread attached to each end of thearticle.

It has been proposed to equip sewing machines with attachments whichwould sever the thread after the stitching operation on each article,but such attachments 'have not proven entirely satisfactory due to thefact' that they'have required some operation on the part of theoperator, were complicated, required modification of the sewing machine,or left a relatively long tail of threads attached to each end of thearticle which was stitched. 4

The present invention provides thread severing means for sewing machineswhich is not open to the above objections to prior thread severing meansfor sewing' machines in that the thread is severed automatically andimmediately after the last stitch upon the article. Furthermore,

of garments, the closing.

to be cut. The cutting succeedingthread loops or the thread chain formedby the continued operation of the sewing machine are destroyed untiljust prior to the introduction of a succeeding article into va positionto be stitched, thereby eliminating not only the thread tail" from bothends of the articles, but also the necessity of the operator to cut thethread between successive articles, and leaving her free to devote herentire time to feeding articles into stitching position.

In accordance with the present invention the sewing machine is providedwith cooperating severing elements which are maintained inoperative aslo'ng as the article to be stitched is between them, but which arebrought into operation to sever the thread immediately upon the passageof the article from between them,

`to the sharp-edged as the thread will be between the 23 claims. (Cl.i12-asa) making the severing operation entirely independent of theoperator, or of the duration of the stitching operation, and insuringthe severing of the thread close to the stitched article. Thecooperating severing elements continue to operate as long as the machineis operating and there is no stitched article between them so that thethread chain or thread loops which are formed between articles arecontinuously destroyed until a succeeding article enters between thesevering elements, when they again are rendered inoperative. f

Contrary to previously proposed means for severing the `thread after thecompletion of the stitching operation on any article, the presentinvention does not depend upon shearing the thread, but severs thethread by crushing it between cooperating ofwhich is mounted to movetoward the other with sumcient forceto cause the thread to be given ablow which will sever it. One of the cooperating severing elements is inthe form of a pressure or anvil member and the other cooperatingsevering element is in the form of a hammer member and may have a sharpedge. 'I'he anvil member preferably is carried by the press'er footofthe sewing machine and preferably is in the form of a freely rotatableroller so that a diiferent surface will continuously be presented hammermember, thereby to prolong the life of the anvil 'I'he hammer member#preferably is carried by andforms a part of the feed dog of the sewingmachine, although it might be formed upon some other part of the sewingmachine, such as a pinking roller, if the sewing machine is providedwith such a roller. When the anvil lessen wear on and member.

member is carried by the presser foot and is' suilicient force that itwill not be raised by an article vto be stitched as it passes beneaththe presser foot. Thus, as long as a stitched 'article is passingbeneath the pressure or anvil member the latter will be raised to aposition where it will not be struck by the hammer member of the feeddog, and the cooperating anvil and hammer members will bemaintained'inoperative, but as soon as the stitching operation on thearticle has been completed neathithe pressure or anvil member, thelatter will be forced down into a position where it can be struck 'bythe hammer member during the normal cycle of movement of the feed dog,and

anvil and hammer during such movement it will be crushed and severed atthe stitch just behind the last stitch on the article due to the factthat the feed thereby dog of a sewing machineV operates in synchronismsevering elements, at least onev the feed dog it is resiliently urgeddownward, but not with and-it has passed from bewith the Ineedle. As thefeed dog continues to operate as long as the sewing machine remains inoperation, the sharp vedged hammer member carried thereby continues tostrike against the anvil as long as there is no stitched article'between them with the result that the entire length l of thread betweenstitched articles is literally masticated or chewed away.

The invention will be further described in connection with theaccompanying drawing but it is to be understood that such furtherillustration and description is by way of exemplification and that theinvention is not limited thereto except to the extent set forth in theappended claims.

In the drawing:

Fig. 1 is a vertical sectional View through a portion of a sewingmachine having the present thread severing means secured thereto.

- fFig. 2 is a horizontalsectional view on line 2-.2 of Fig. 1.

Fig. 3 is a vertical sectional View on line 3 3 of Fig. 1.

Fig. 4 is a more or less diagrammatic view i1- lustrating how the threadbetween stitched articles-is chewed away, andt l Fig. 5 is a perspectiveview of the presser foot member of the present device. l

The present invention may be applied to lockstitch sewing machines,chain-stitch sewing ma.- chines, over-edgers, two needle sewingmachines, or any other type of sewing machine where the articles to bestitched are passed successively throughthe stitching position.

For purpose of illustration, the invention is shown in the accompanyingdrawing as applied to a plain lock-stitch sewing machine having theusual head I which carries a presser foot bar 2 and needle 3. The sewingmachine also has the usual work-supporting bed-plate 4 provided with athroat plate 5 having an opening 6 .for the needle and parallel slots 1,3 and 9 for the feeding teeth of a feed dog -Ill. The usual mechanism, apart of which is shown at II, is provided to impart theback and forthand up and down movement to the feed dog to feed the articles to bestitched through the sewing machine in the direction indicated by thearrow. l

In the preferred form of the invention, the usual presser foot of thesewing machine is replaced' by a presser foot assembly which is securedto the lower end of the presser foot bar 2 by the usual thumb screw I2.The presser foot assembly comprises a vertically-extending shank memberI3, a sole-plate I4, and a U-shaped yoke member I3 having a base portionI5* and forwardly-extending arms I5. The upper part I6 of the shankmember I3 is bent in rectangular or other appropriate shape to conformto the shape i of the lower end of the presser foot bar 2 and is adaptedto be slipped-over the lower end of the presser foot bar 2 and securelyheld thereto by the thumb screw I2 which is received in a slot I1 in oneside of the upper portion I6 of the member I3. The lower end of themember I3 is provided at each side with a forwardly-extending ear I3,and the sole-plate I4 is provided interme- 'diate its length with a pairof upwardly-extending ears I9. A pivot pin 20 extends throughlthe earsI3 and I3 and through the forwardly-extending arms I5b of the yokemember I5 so that the yoke member has a swinging movement in a verticleplane about said pin as will hereinafter appear.

The vertically-extending member I3, the soleplate Il, and the yokemember I5 preferably are die-stamped to maintain the cost of manufactureas low as possible, but if desired those parts may be cast, in whichcase the vertically-extending member I3 and the sole-plate I4 may bemade integral. y

A pressure or anvil member in the form of a roller 22 having flanges 23at each end thereof is mounted for free rotatable movement on an axispin 24 extending between the arms lh of the yoke member, and rearwardlyof the vertically-extending member I3 and in alignment with the needle 2of the sewing machine.

'I'he rear portion I5 of the yoke member and the roller 22 carriedthereby are normally urged downwardly by a spring 25 interposed betweenthe member I3 and the base I5 of the yoke member. The forward end of thespring is received in a recess or socket 26 in the rear face of themember I3, and in order that the force with which the spring will urgethe rear of the yoke member and the roller carried thereby downwardlymay be adjusted, the rear end of the spring bears against the shoulderon an adjusting screw 21 extending through the base of the yoke member.A lock nut 28 holds the screw in adjusted position.

The presser foot sole-plate I4 is formed with the usual upwardly curvedsplit toe portion 29 under which the articles to be stitched are fed,and through which the needle passes. InY order to provide a moreextending gripping surface, the bottom of the sole-plate is made longerthan usual, and the rear part thereof is bifurcated to provide anopening 30 through which the pressure or anvil roller extends.

The feed dog is similar to feed dogs now used in sewing machines andincludes portions having feeding teeth 3| which extend through the slots1, 3 and 3 to engage the articles to be stitched to feed them throughthe sewing machine. However, the feed teeth which pass through thecentral slot 3 extend rearwardly a sufiicient distance to bring the reartooth 32 beneath the roller 22 when the feed dog is in its upward andback position. The rear tooth 32 of the feed dog preferably is formedwith a knife edge and when the sewing machine is operating and there isno article to be stitched between it and the anvil member, it cooperateswith the anvil member, as a hammer, to sever the thread loops formed bythe stitching mechanism. The

-anvil roller 22 and the feed dog, including the hammer tooth 32 havingth'e knife edge, are made of hard steel to withstand the wear to whichthey are subjected. In order to better guide the series of chain loopsof the chain thread connecting stitched articles beneath the roller 22,the innerl end portion of the part of the feed dog which extends throughthe slot 3 is provided with a thread guiding groove 33, preferablyV-shaped in top plan and having its apex portion disposed upwardly andrearwardly, as illustrated in Figs. 1 and 4.

,As will be seen from Fig. 3, the flanges 23 of the anvil roller overliethe portions of the throat plate between the slot 3 and the slots 1 and9 at ber I5 and the roller 22 are in their lowermost position, the-anges 23 will rest upon and be supported by those portions of thethroat plate. Consequently, in the absence of work, the face portion ofthe roller 22 between the flanges 23 thereof and with which portion ofthe roller the Obviously, as the roller 22 passing under the flanges'roller opposed to the hammer tooth 32 is correspondingly elevated,thereby obviating marring of thefs'titchcd work by the sharp edge of themetan.

The spring 25 constantlytends to swing the rear part of the yoke memberl and the anvil roller 22 carried thereby downwardly about the pivot pinsothat the portion of the roller between the flanges 23, which is inalignment with the needle 3 and the guiding groove 33 of the feed dog,will be struck by the knife edge of the hammer tooth 32 of the feed dogonce during each cycle of the movement of the feed dog.v However, assoon as the article being stitched is fed backwardly` through the sewingmachine' far enough to come beneath the roller 22 it raises the rolleraway from the path of movement ofthe feed dog suiiiciently that thehammer tooth 32 of the feed dog no longer cooperates with the roller toeffect a severing action and'that tooth like the other ofthe feed teethmerely functions to feed the articles through the sewing -needle will bethreaded when ticle is inserted into stitching position.

The chewed or mastcated portionsof `the thread,

shown at 3l in Fig. 4, will be brushed away by the feeding of thefollowing stitched article through the sewing machine.

During the severing of the thread loops attached to a stitched articleand thereafter the extended lower surface'of the presser foot soleplateI4 holds the machine end of the thread between the cooperating severingmembers and the needle sov that it cannot fly back through the Y eye ofthe needle on thev next upward movement of the needle bar, and therebyinsures that the `As it naturally requires a greater compressive forceto crush a coarse thread until -it is severed than it does to crush afine thread, the tension which the spring exerts to move `the roller 22downwardly towards the tooth -32` .will be adjusted in accordance withthe weight 4o f the thread being used at any particular time.

From the foregoing description it will be seen that the presentinvention provides a device for machine. As soon as the vstitchedarticlepasses beyond the Vvertical center of the roller 22 the spring 25 forcesthe roller downwardly .to a position where it will be struck by the.hammer tooth 32 in` the next upward rear movement of thel The centralpart of the roller 22F being in alignment with the needle of the sewingmachine and the guiding groove 33 of the feed dog,fthe chain loopsformed bythe continued operation of the sewing machine will lie beneaththe roller which acts like an anvil to back up the thread when it isbeing struck by the knife edge of the hammer tooth 32. As the roller 22is freely rotatable on the axis pin 24, and as the feed dog movesthrough a counter-clockwise path which is generally elliptical, the edgeof the tooth 32 as it strikes the thread lying against the roller; willnot onlyl crush the thread until itv breaks, but

also will cause a slight rotative movement of the roller so that a newstriking surface of the roller will constantly be presented to the tooth32, thereby greatly prolonging the life of the anvil roller. 4

As the mechanism for operating the feed dog is synchronized with themechanism forv operating the needle so that the feed dog moves throughits cycle once for each stitch which the needle makes, it will beapparent that the maximum length of the thread left at the end of aofthe stitch for which'the sewing machine ,is

uen it wm be struck by the teeth 32 'during each "stitched article willb e substantially the lengthi severing the "tail of thread on a stitchedarticle by crushing it between cooperating hammer and anvil membersuntil it breaks, as distinguished from prior devices where the severingof the thread has been by a shearing actio'n, as with shears or othercooperating shearing blades. Also, the present invention provides adevice which is wholly automatic in its operation and which'not onlysevers the tail of thread on a stitched article at the stitch followingthe last stitch madeon the article but also masticates or chews away theentire chain of thread loops between successive articles up to'v aninitial stitch on a following article, so that the tail of thread iseliminated from both ends of the article.

While the invention is particularly adapted for sewing machines in whichsuccessive articles to be stitched are fed through the sewing machine vor anvil member carried bythe presser foot for coaction with saidsevering member to sever a thread passing between said severing memberand the pressure or anvil member, said pressure oranvil member being.mounted Vfor movement toward or from the severing member and being movedfrom the severing member to an inoperative position'by a stitchedarticle tween it and said severing member.

2 .f1n a sewing machine having a feed dog and passing bea presser foot,athread severing member carried cycle of movement of lthe feed dog.'Ihus the chain of thread loops formed between the final stitch upon onearticle and thevinitial stitch on the succeeding article, by thecontinued operation of the sewing machine, will -repeatedly be subjectedto the cooperating severing action of the roller 22 and the hammer tooth32, with the result that the entire chain of thread loops will bemasticated-or chewed away until the very instant the succeeding articleisfed rearwardly far enough to pass beneath the roller 22 and therebyraise the roller again to its inoperative position.

by the feed dog, a pressure' or anvil member carried bythe presser footfor movement toward and from the 4severing member` carried by the feedVdog, and a `spring member for resiliently urging 4thebpressure or anvilmember toward the severing member carried bythe' feed dog.

3. In a sewing machine having a feed dog and a coacting presserfoot, aseveringmember carriedby the f eed dog, a member pivotally connected tothe presser foot for movement toward orvfrom the feed dog, a rotatingpressure or anvil member carried by said movable member for a succeedingari coaction with the severing member of the feed dog, and meansengaging said movable member for constantly urging the pressure or anvilmember toward the severing member carried by the' feed dog.

`fl. A sewing machine having a feed dog and a coacting presser foot, asevering member carried bythe feed dog, a member pivotally connected tothe presser foot for movement toward and from the feed dog,l arotatingpressure or anvil member carried by said movable member for coactionwith the severing member of the feed' dog, and means engaging themovable member for constantly and resiliently urging said pressure oranvi1 member toward said severing member, said pressure or anvil memberbeing moved away from the feed dog to a position inoperative tocooperate with said severing member by the interposition of a stitchedarticle between it and said severing member.

5. In a sewing machine having a presser foot and a feed dog,arotarypressure oranvil mem- `ber carried by the presser foot, and asevering hammer tooth carried by the rear portion of the feed dog andadapted to cooperate with said rotary` pressure or anvil member to severthread ati tached to a stitched article.

6. In a sewing machine'having a presser foot and a feed dog, a rotarypressure or anvil member carried by the Vpresser foot and mounted tomove toward and frornthe feed dog, spring means normally urging saidrotary pressure or anvil member toward said feed dog, and a severingtooth carried by the rear `portion of said feedY dog for cooperatingwith said pressure or anvil member when it is in its position nearestsaid feed dog, to sever thread attached to a stitchedarticl.

'7. Ina sewing machine, a presser foot assembly including a presser footportion and a yoke having forwardly-extending arms, a rotary pressure orhammer member mounted between said arms, spring means normally urgingsaid yoke and pressure or hammer member towards the path of stitchedarticles through the machine, a feed dog, and a sharp-edged hammer toothcarried by the rear portion of said feed dog for cooperating with saidrotary pressure or anvil member to sever thread attached to a stitchedarticle, said yoke member and the pressure or the threads connectingsuch articles comprising a pressure or anvil member carried by thelpresser foot, a hammer member having a sharp edge carried by the feeddog of the sewing machine adapted to cooperate with said pressure oranvil member, means normally urging said pressure or anvil member to aposition operative to cooperatewith said hammer member, said pressure oranvil beingraised to an inoperative position by the interposition of astitched article between said pressure or anvil member and said hammermember but again being returned to a position operative to cooperatewith said hammer member'immediately upon the passage of an article frombetween them whereby upon continued operation of the sewing machine saidpressure or anvil member and said hammer member continue to.

cooperate to chew or masticate the threads connecting successivearticles from immediately after the passage of one article from betweensaid members until immediately prior to the entry of a succeedingarticle between them.

9. In a sewing -machine a presser foot assembly adapted to be detachablyconnected to a presser foot bar of a sewing machine and comprising apresser foot member, a generally U- shaped Ayoke member having the armsthereof extending forwardly, a rotary pressure or anvil member mountedbetween said forwardly-extending arms of the yoke member and means fornormally and resiliently urging said yoke member and the pressure oranvil member carried thereby texan operative severing position, and asevering member'carried by the rear portion of the feed dog of thesewing machine and adapted, when said pressure or anvil member is in itsoperative severing position, to cooperate therewithto sever threadsinterposed between them.

10. In al sewing machine, a rotary pressure or anvil member carriedbythe presser foot of the sewing machine, means for normally andresiliently urging said pressure or anvil member to an operativesevering position, said pressure or anvil member having aradially-extending flange at the ends thereof adapted to bear upon aportion of the throat 4plate of the sewing machine to support thepressure or anvil member when the pressure or anvil member is in itsoperative severing position, and a severing member carried by the feeddog Vof the sewing machine and adapted to cooperate with the portion ofthe pressure or anvil member` between the end flanges thereof rto severthread interposed between said severingv member and the pressure oranvil member-when the latter is in its operative severing position, saidpressure or anvil member being moved to a position inoperative tocooperate with said severing member by the interposition of a stitchedarticle between them but being returned to operative severing positionimmediately upon the passage of said ,article from between them4 11'. Ina sewingmachine having apresser foot and a feed dog, a workfresponsivesevering member located behind said presser foot, a severing membercarried by the feed dog and adapted dury ing the movement of the feeddog to cooperate behind said presser-foot iwith saidrst-mentionedservering member to sever thread attached to a stitchedarticle, said presser lfoot holding the machine endof the thread after asevering operation to prevent unthreading of the sewing machine needle.

12. In a sewirg machine, a feed dog, a severing member carried by thefeed dog, a second severing member for cooperating with the severingmember carried by the feed dog located at the side of the path ofstitched articles passing through the sewing machine opposite the feeddog, said second severing member being mount- A ed for movement towardand from the' severing member carried by the feed dog, and being movedaway from saidl severing member to an inoperative position by theinterposition of a stitched article between it and the severing membercarried by -thefeed dog. r

13. In a sewing machine, a feed dog, av severing member carried by thefeed dog, a pressure or anvil member for cooperating with said severingmember 'located at thel side of they path of stitched articles passingvthrough the sewing machine opposite thefeed dog, said pressure or anvilmember being mounted for movement toward and from the severing memberand being movedgaway from said severing member to an inoperativeposition by the interposition of a stitched article between it 'and thesevering member carried by the feed dog.

' 14. In a sewing machine, a feed' dog, a severing member carried by thefeed dog, ya second severing memberfor cooperating with the severingmember carried'by the feed dog located at the. side of the path ofstitched articles passing through the sewing machine opposite the feeddog, spring means for normally urging said second severing member towardthe severing member carried by the feed dog, said second severing memberbeing moved away from the severing member carried by .the feed dog to aninoperative position by the interposition of a stitched article betweenit and the severing member carried by the feed dog.

15. In a sewing machine, a feed dog. a severing member carried by thefeed dog, a pressure or anvil member for cooperating with said severingmember located at the side-of the path of stitched articles passingthrough the sewing machine opposite the feed dog, spring means fornormally urging said pressure or anvil member toward said severingmember, the pressurewith which vsaid spring urges said pressure or anvilmember to- 39 ward said severing member being such that the pressure oranvil member will be moved away from said severing member to aninoperative position by the interposition of a stitched article betweenthe pressure or anvil member and the being disposed in spaced relationto 'said wrko support in the absence of work, and means effective uponoperation of the machine for imparting uniform operative movements tosaid complemental thread-severing member in successive stitch-formingcycles.

17. In a sewing machine having stitch-forming mechanism including areciprocatory needle, two cooperating thread-severing membersclisnosedrearwardly of the path of needle reciprocation and maintainedseparated by work passing through the machine, one of said membersbeine,` movable in the direction of travel of the work and the otherbeing movable in a direction substantially normal tothe plane ofthe workinto` thread-severing engagement with Veach other. 55

18. In a sewing machine having stitch-forming mechanism including areciprocatory needle. a

presser-foot. two lcooperatingthread-severing l members maintainedseparated by work passing through the machine, one of said members beingmovable inthe direction of travel of the work and the other beingmovable relative to the presser-foot in a direction substantiallynormalto the plane of the work into' thread-severing y engagement with eachother.

19. A sewing machine having a needle, a feeddog, a throat-plate havingneedle and feed-dog clearance apertures, means for imparting workvadvancing movements to said feed-dog, said feed-dog having athread-severing edge disposed in rear of said needle-aperture, aspring-pressed presser-foot having `a planar work-engaging surfaceopposed to said feed-dog, and complementary thread-severing meansdisposed in rear of the planar work-engaging face of said presserfootand in rear of the thread-severing edge of the feed-dog as the latterbegins its feed-stroke, said complementary thread-severing means be-'ing yieldingly urged towards said throat-plate for 4 engagement by saidthread-severing edge in the absence of work, whereby the thread trailingrearwardly from the stitching point of the machine will be severed whensaid thread-severing edge of the feed-dog, in the feed-stroke of thelatter, engages said complementary thread-severing means.

20.l In a thread-chain severing device for sewing machines, apresser-foot having a supporting shank, a work-.engaging sole-platecarried by said presser-foot shank and provided with a needle-aperture,a work-responsive member pivotally mounted upon and extending rearwardlyfrom said shank for movement about an axis transverse to the length ofsaid sole-plate, and a thread-chain severing element carried by saidmember for movement into and out of the plane of the work-engaging faceof said sole-plate.

21. In a thread-chain severing device for sewing machines, apresser-foot having a supporting shank, a work-engaging sole-platecarried by said presser-foot shank and provided with. a needle-aperture,a work-responsive member pivotally mounted upon and extending rearwardlyfrom said shank for movement about an axis transverse to the length ofsaid sole-plate, a peripherally flanged roller journaled upon saidmember for turning movements about an axis substantially parallel to thepivotal axis of said member, said roller providing a peripheralanvilface movable into and'out of the plane of the work-engaging face ofsaid sole-plate.

22. In a thread-chain severing device for sewing'machines, apresser-foot having a supporting shank, a wor -engaging sole-platecarried by said presser-foot shankv and provided with a,needle-aperture, a work-responsive member pivotally mounted upon'andextending rearwardly from said shank for movement about an a'xistransverse to the length of said sole-plate, a thread-chainseveringelement carried by said member, a, spring bearing uponv saidmember in a direction to depress saidsevering element to- -wards theplane of the work-engaging face oi' said sole-plate, and means providingfor adjustment of the pressure of said spring upon said member. f

23. In a sewing machine, including a presserfoot and a. feeder movablerelative to the foot.

' means carried by the presser-foot and feeder for cooperativeh actionto sever a thread drawn therebetween by a piece of material as thelatter thread remaining attached to the machine needle after the threadhas been severed.'

'THOMAS A. ANDERSON.

